Modeling characters is very interesting and sometimes may be hard. Many 3D artists admitted that modeling eye is one of the hardest parts of their work. However, eyes make human models very realistic if they look realistic and vice versa. Arrimus 3D prepared a short but very useful tutorial for modeling, texturing, and rendering an Eyeball:

And the second part:

If you are looking for 3D models to buy or for inspiration, check FlatPyramid’s models.

Here you can easily upload your models for selling on FlatPyramid.